An electricity storage unit includes: an electricity storage device; a circuit portion on which an electronic component is mounted; a heat dissipation member that dissipates heat from the circuit portion; and a holding member that holds the electricity storage device in a state where the electricity storage device, the circuit portion, and the heat dissipation member are stacked, wherein the holding member is provided with a supporting portion that supports the electricity storage device and abuts against the heat dissipation member.